A testing method using spectroscopic photometry with three wavelengths of light and a device for carrying out the method

Abstract

 For detecting a leak in a transparent or semitransparent vessel (5) by a dye bath method, the light passing through the vessel (5) is divided into three wavelength regions, that is light having the characteristic wavelength of the dye bath liquid, light of prescribed wavelength having a wavelength shorter than said light and light of prescribed wavelength having a wavlength longer than said light, and the curvature of the transmittance curve based upon difference values of transmittance among three lights having different wavelengths is obtained for comparing with a preestablished value to judge the vessel (5) to be inferior or normal with respect to the compared output.

Description

[0001] The present invention relates to a testing method and a device for the testing method according to spectro-photometry technology using three wavelengths of light with which a leak in a vessel, more specifically a leak in an ampoule, can be detected with a dye bath technique, for example a blue bath method.

[0002] When a pinhole is brought about in a glass ampoule or a vial for a chemical liquid or a liquid of food, or when an ampoule is not perfectly hermetically sealed, a leakage or a bacillary pollution may be caused.

[0003] Accordingly, a dye bath technique such as the blue bath method is utilized, in that when an ampoule is dipped into a dense blue dye solution, for example a solution of methylene blue or other blue dye for food, and is evacuated once and then brought back to an atmosphere of normal pressure, this dense dye solution will be introduced into the ampoule through small holes, cracks or gaps of the glass wall if the ampoule is of inferior quality. An inferior ampoule is eliminated by detecting the colour of the introduced dye solution. Conventionally such ampoule containing dye solution has been found by the visual inspection of the colour of the dye solution in the ampoule. There has been a detection limit for this method. Further, it has been difficult to detect failures in case of a coloured ampoule or a coloured solution.

[0004] Therefore, for measuring the light energy transmitted through the ampoule with an optical detection method, a measuring method using two-wavelength spectro-photometry is set forth in Japanese Patent Application 54-133183 (Priority U.S. Serial No. 869554).

[0005] In the measuring method using two wavelength spectro-photometry, the light passing through a vessel and the contents in the vessel is received, and divided into two beams with optical cables. A standard filter is provided for one beam to filter a light of wavelength uninfluenced by the characteristic wavelength as of the dye and a target filter being provided for the other beam to filter the characteristic wavelengthof the dye. The outputs from filters are detected as electric signals. These two output signals are mutually added and subtracted for obtaining the sum and the difference. In comparison with these values, the subject is judged to be good or inferior.

[0006] However, even in the measurement by two wavelength spactro-photometry, when the vessel such as an ampoule is coloured for example brown, the difference in colour of the individual ampoules causes the absorption in the wavelength for the measurement change. Therefore, even a good ampoule can be judged to be out of the judging region for a-good one resulting in an inferior detection sensitivity.

[0007] Further, in case of an ampoule containing coloured liquid, the temperature change of the contents itself causes the absorption to change, affecting the result of the measurement.

[0008] The object underlying the present invention is to decrease the influence of changes as to absorption caused by the dispersion of the degree of colouring of a coloured ampoule, e.g. so-called amber ampoules and temperature changes.

[0009] As the amber ampoule is employed for eliminating shorter wavelengths, the delicate difference in the degree of colouring causes the absorption in a shorter wavelength region to be measured incorrectly. The influence of the wavelength characteristic cannot be avoided in the conventional two wavelengths spectro-photometry as described above.

[0010] Another object is to decrease the influence of the change of absorption corresponding to the temperature of the contents when the characteristic wavelength of the ampoule itself is in the measuring wavelength region.

[0011] For example, as shown in Fig. 1, curves are obtained from the measurement of transmittance for a vacant ampoule coloured in dense brown F(R) and a vacant ampoule coloured in comparatively light brown F(0). The transmittance values of the lightly coloured vacant ampoule F(0) at wavelength values of 570 nm, 630 nm and 720 nm are respectively expressed by al, a2 and a3, and those of the densely coloured vacant ampoule F(R) at the same wavelengths as for F(0) by bl, b2 and b3.

[0012] The differences between F(R) and F(0) in the vicinity of the wavelength of 550 to 660 nm and those in the vicinity of 600 to 650 nm and 700 to 750 nm are different from each other, and the gradient of a line connecting al and a3, at al is different from that of a line connecting bl and b3 at bl. However, these curves are similar in shape. The wavelength of 630 nm is the characteristic wavelength of the dye (Food blue No. 1). The wavelength of 570 nm and that of 720 nm are the standards set for comparison.

[0013] In case of measurement using two wavelengths, if the transmittance at the wavelength of 630 nm and that at the wavelength of 720 nm are compared, the difference (a3-a2) for the lightly coloured ampoule F(0) is smaller than the difference b3-b2 for the densely coloured ampoule F(R). Although vacant ampoules which are not affected entirely by contents are used, such differences as described are caused, which may be beyond the quality judging region making the accuracy of judgement inferior.

[0014] However, when the measurement using three wavelengths according to the present invention is employed, the measurement results are practically not affected by the colouring degree of the ampoule. Accordingly, the shape of the transmittance curve is not influenced by the colouring degree of the ampoule. Particularly, when y is the intersection of a vertical line at the wavelength of 630 nm and the straight line connecting a3 and al, a difference (a2-y) is expressed as A, which is the so-called depth of curve of the empty ampoule F(0). The depth of curve is a value for approximately determining the curvature of a curve. For the empty ampoule F(R), x is the intersection of a vertical line at the wavelength of 630 nm and a straight line connecting b3 and bl, being expressed as B. The form and the depth of curve of the empty ampoule F(0) are almost the same as those of the empty ampoule F(R), therefore A is nearly equal to B.

[0015] Thus, the depth of curve A and that of B are not influenced so much by the degree of colouring of the ampoule. Therefore, when Food blue No. 1 is employed for example as a dye for a blue bath, an inferior ampoule which the dye has leaked into has its absorption increased and its transmittance decreased, and the depth of curve assumes a smaller value compared with the differences A or B as a fixed standard value. If the ampoule having a characteristic which is judged as an inferior one, an exact selection is performed without being affected by the gradient of curve and the absolute value of transmittance.

[0016] Fig. 2 shows the transmittance characteristic P of coloured liquid contents at room temperature (18°C) and the transmittance characteristic Q of the same liquid heated to 60°C. As is obvious from Fig. 2, at a high temperature the changes of the transmittance characteristics Q at the longer wavelengths and the shorter wavelengths are symmetric with the characteristic wavelength 630 - 670 nm as a symmetric axis. However, the shape of P and Q is almost the same.

[0017] The measured transmittance at 18°C of the coloured liquid at the wavelengths of 570 nm, 630 nm and 720 nm are respectively expressed as Cl, C2 and C3, and the same at 60°C as dl, d2 and d3. When the intersection of a straight line connecting Cl and C3, and a vertical line at the wavelength of 630 nm is k, the difference between C2 and k is taken as C. Similarly, when the intersection of a straight line connecting dl and d3, and a vertical line at the wavelength of 630 nm is 1, the difference between d2 and 1 is taken as D. The difference C is almost equal to the difference D. Accordingly, if C and D are taken as the standard values, the value of transmittance of an inferior ampoule which the dye bath liquid has leaked into is lower than said standard value for easy judgement.

[0018] The selection of three points in wavelength may be performed at will according to the characteristic wavelength of a dye of a dye bath, and an ampoule or the contents in an ampoule regarding the peak value of methylene blue is in the vicinity of 660 nm and the peak value of Blue No.1 dye for food is in the vicinity of 630 nm.

[0019] Other and further objects and features of the present invention will be apparent from the following description taken in connection with the accompanying drawing, in which

Fig. 1 shows transmittance characteristic curves of a densely coloured empty ampoule and a lightly coloured empty ampoule,

Fig. 2 shows transmittance characteristic curves of a coloured content in an ampoule at room temperature (l8°C) and that in a heated state (60°C),

Fig. 3 is a schematic diagram showing an embodiment of the testing device according to the present invention, and

Fig. 4 is a block diagram to illustrate a concrete embodiment of the electric circuit member of the testing device according to the present invention.

[0020] An embodiment of the testing device according to the invention will be described referring to Figures 3 and 4.

[0021] In Fig. 3, 1 is a projector lamp as a light source. For the projector lamp l, an objective lens 2, e focussing lens 3 and a light receiving member 4 are sequentially arranged. An ampoule 5 as a subject to be tested is arranged between the objective lens 2 and focussing lens 3.

[0022] The light receiving member comprises microlight receivers 4a, 4b, ... such as light guides divided into a plurality of small sections such as glassfibers corresponding to the detection limit of foreign matter or substances. The output side of respective microlight receivers 4a, 4b,... is connected to a detection device 6 for foreign matter in the ampoule 5. A light guide 4d for example for one bit is introduced from one section of the microlight detectors or receivers 4a, 4b, .... At the tip of the light guide 4d there are two prism filters, namely a first and a second prism filter, connected through a condenser 7. The light beam or bundle passed through the condenser 7 is divided into three, one refracted by the first prism filter 8, one refracted by the second prism filter 9 after having passed through the first prism filter 8, and one having passed through the first and second prism filters 8 and 9. A wavelength filter 10 for selecting the characteristic wavelength of the dye bath liquid is provided for the light refracted by the second prism filter 9. For the light refracted by the first prism filter 8 and the light passed through the first and second prism filters 8 and 9, respective standard wavelength filters are provided. The output sides of the respective wavelength filters 10, 11 and 12 are connected to a comparator 19 through photoelectric transfer elements 13, 14 and 15, respectively, and amplifiers 16, 17 and 18, respectively. The comparator 19 is connected to an output terminal 21 through a comparator 20. The other input side of the comparator 20 is connected to an input terminal 22 for inputting a standard value for judgement Z which is prescribed to correspond to said difference A = B.

[0023] A concrete circuit following the photoelectric transfer elements 13, 14 and 15 in Fig. 3 is shown in Fig. 4, in which 13, 14 and 15 as shown in Fig. 4 are photoelectric transfer elements comprising photodiodes for example. These photoelectric transfer elements output electric signals corresponding to the transmittance of light, the wavelengths of which are for example 630 nm, 570 nm and 720 nm. These photoelectric transfer elements 13, 14 and 15 are connected to preamplifiers 23, 24 and 25, respectively, and gain adjusting amplifiers 26, 27 and 28, respectively, comprising the amplifiers 16, 17 and 18. Of these gain amplifiers 26, 27 and 28, two gain amplifiers 26 and 27 are connected to a comparator 29, two gain amplifiers 27 and 28 are connected to a comparator 30, and these comparators 29 and 30 are further connected to a comparator 31 and to the comparator 20 through the comparator 31. The comparators 29, 30 and 31 comprise the comparator 19 in Fig. 3.

[0024] The manner of functioning of the device according to the present invention will be described hereinafter.

[0025] In Fig. 3 an ampoule 5 as a subject to be tested is dipped into a dense blue dye solution, such as methylene blue or blue dye for food, and then evacuated. The dense dye solution will be introduced into the ampoule through some pinholes, cracks and gaps if the ampoule 5 has any of these faults. The ampoule 5 thus pretreated is set continuously between the objective lens 2 and the focussing lens 3 by a supply device (not shown). The ampoule 5 thus set is revolved in a high speed and stopped quickly. A foreign substance, if any, mixed into the solution will float and be detected by any one of the microlight receivers 4a, 4b, ..., and a signal obtained by detection is inputted to the foreign substance detecting device 6 to eliminate such ampoules 5 which contain foreign substances.

[0026] When the ampoule 5 itself has pinholes or the like and the dense dye solution is introduced into the ampoule 5, the light transmitted through the ampoule 5 is coloured, and the coloured light is introduced into the light guide 4d to be irradiated from the tip of it. The irradiated light made parallel by the condenser 7 passes through the first prism filter 8, is refracted by the second prism filter 9, passes through the wavelength filter 10 which selects the characteristic wavelength of the dye bath liquid, is transformed into an electric signal in the photoelectric transfer element 13, and is transmitted to the comparator group 19 through the amplifier 16. In the comparator group 19, the signals obtained in a similar way for the standard value are measured for absorption values, or transmittance values of three wavelengths for comparison. The resulting values computed from these comparisons are outputted as an analogue signal.

[0027] More particularly, respective output signals corresponding to the transmittance of rays at the wavelengths of 630 nm, 570 nm and 720 nm are amplified by respective preamplifiers 23, 24 and 25, respectively, having their gain adjusted by the gain adjusting amplifiers 26, 27 and 28 to be entered into the comparators 29 and 30.

[0028] Now, for obtaining the difference A of the ampoule F(0) in Fig. 1, y is obtained as follows:

therefore, the difference A is

Based upon the formula, the comparator 30 is inputted with output al at the wavelength of 570 nm and output a3 at the wavelength of 720 nm, outputting

(a3-al), which is the difference (a3 - al) multiplied by a constant (

) and gain-adjusted. The comparator 29 is inputted with the output al at the wavelength of 570 nm and the output a3 at the wavelength of 630 nm, outputting the difference a2 - al. Then, in the comparator 31 the difference of these outputs a2 - al and

(a3-al) is obtained for outputting an output signal A, namely

[0029] In a similar way, the difference C for the characteristic curve P can be obtained to be outputted from the comparator 31 as:

The differences A or C thus obtained are compared with the judging standard value Z inputted from the input terminal 22. When the difference A or C is lower than the standard Z, a signal that judges an ampoule to be inferior is outputted from the comparator and a solenoid or the like (not shown) is excited for eliminating the inferior ampoule.

Claims

1. A testing method using spectro-photometry with three wavelength values for optically detecting a leak in a transparent or semitransparent vessel (5) by a dye bath method, wherein light passing through the vessel (5) is divided into three parts, light having a characteristic wavelength of the dye bath liquid, light of a prescribed wavelength, having a wavelength shorter than the characteristic wavelength of dye bath liquid and light of a prescribed wavelength having a wavelength longer than the characteristic wavelength of the dye bath liquid for obtaining the curvature of transmittance curves from differences of transmittance values of these three wavelength values, comparing the curvature with prescribed value, and judging the vessel as to whether it is good or inferior by the output obtained through the comparison.

2. A testing method using spectro-photometry with three wavelength values according to claim 1 wherein an intersection of a straight line connecting the transmittance values of the light having a shorter wavelength and the light having a longer wavelength and a vertical line at the wavelength of the dye bath liquid is obtained for a difference of the transmittance value at said intersection and that of the dye bath liquid so as to determine the curvature of the curve.

3. A testing method using spectro-photometry with three wavelength values for optically detecting a foreign substance in the contents of a coloured liquid filled in a transparent or semitransparent vessel (5) comprising a light source (1), a light receiving member (4) for a light beam or bundle from the light source (1) passing through the vessel (5) or a liquid in the vessel (5), three optical filter means (8 - 12) for generating optical signals in three freely selected wavelength regions out of the beam or bundle from the light receiving member (4), three optical detector means (16, 17,18) for providing three output signals respectively presenting optical signals from the three optical filter means (8 - 12), and comparator means (19, 20) for comparing compared values obtained by mutual comparison of the output signals with the prescribed standard value for judgement.

4. A testing method using spectro-photometry with three wavelength values according to claim 3 wherein the three optical filter means (8 - 12) comprise a first and a second prism filter (8, 9), and wavelength filters (10, 11, 12) for selecting respective specific wavelength values from the refracted light at the first prism filter (8), the refracted light at the second prism filter (9) after passing through the first prism filter (8) and light passing through the first (8) and the second prism filter (9).

5. A testing method using spectro-photometry with three wavelength values according to claim 3 or 4 wherein the comparator means is composed of a comparator (29) for providing a difference of transmittance values for light of the characteristic wavelength of the dye bath liquid and for light of prescribed wavelength having a shorter wavelength than the characteristic wavelength of the dye bath liquid, a comparator (30) for providing a difference of transmittance values for light of prescribed wavelength having a longer wavelength than the characteristic wavelength of the dye bath liquid and light of prescribed wavelength having a shorter wavelength than the characteristic wavelength of the dye bath liquid, a comparator (31) for obtaining the curvature of transmittance curve from these differences, and a comparator (20) for comparing the curvature of said curve with a prescribed standard value for judgement.

6. A testing method using spectro-photometry with three wavelength values according to any of claims 3 to 5, wherein the light receiving member (4) comprises an aggregate of microlight receivers (4a, ... 4n) divided into a plurality of small sections corresponding to the detection or the foreign substance, one small section (4d) of the aggregate (4) being extended for detection of pinholes.

7. A testing device using spectro-photometry with three wavelength values for optically detecting a foreign substance in the contents of a coloured liquid filled in a transparent or semitransparent vessel (5) comprising a light source (1), a light receiving member (4) for a light beam or bundle from the light source (1) passing through the vessel (5) or a liquid in the vessel (5), three optical filter means (8 - 12) for generating optical signals in three freely selected wavelength regions out of the beam or bundle from the light receiving members (4), three optical detector means (16, 17, 18) for providing three output signals respectively presenting optical signals from the three optical filter means (8 - 12), and comparator means (19, 20) for comparing compared values obtained by mutual comparison of the output signals with the prescribed standard value for judgement.

8. A testing device using spectro-photometry with three wavelength values according to claim 7, wherein the three optical filter means (8 - 12) comprise a first and a second prism filter (8, 9), and wavelength filters (10, 11, 12) for selecting respective specific wavelength values from the refracted light at the first prism filter (8), the refracted light at the second prism filter (9) after passing through the first prism filter (8) and the light passing through the first and the second prism filter (9).

9. A testing device using spectro-photometry with three wavelength values according to claim 7 or 8, wherein the comparator means is composed of a comparator (29) for providing a difference of transmittance values for light of the characteristic wavelength of the dye bath liquid and for light of prescribed wavelength having a shorter wavelength than the characteristic wavelength of the dye bath liquid, a comparator (30) for providing a difference of transmittance values for light of prescribed wavelength having a longer wavelength than the characteristic wavelength of the dye bath liquid and light of prescribed wavelength having a shorter wavelength than the characteristic wavelength of the dye bath liquid, a comparator (31) for obtaining the curvature of transmittance curve from these differences and a comparator (20) for comparing the curvature of the curve with a prescribed standard value for judgement.

10. A testing device using spectro-photometry with three any of wavelength values according to claims 7 to 9, wherein the light receiving member (4) comprises an aggregate of microlight receivers (4a, ..., 4n) divided into a plurality of small sections corresponding to the detection limit of the foreign substance, one small section (4d) of the aggregate (4) being extended for detection of pinholes.

Drawing